Cast fixed bridge



April .0- c. D. MORTON .1 6.505

CAST FIXED BRIDGE Filed March 31, 1938 2 Sheets-Sheet 1 AZZorneyJ April 9, 1940. c, D, MQRTQN 2,196,505

I CAST FIXED BRIDGE Filed March 31, 1938 2 Sheets-Sheet 2 I K k I Ai y/22,

5 fliiornega.

Patented 9, 194 O UNITED STATES PATEN?.bFFICE;

7 2,196,505 oAsr FIXED BRIDGE a v v I Charles DaleMorton,Greenfield, Ind.

' applicant March 31 1938, serial No. 1199,12?

a s Claims. (01. 326) l a v This invention relates to the art of dental Reference is made tofm'y U.-S. Letters Patent bridge work and has for a primary object the No. 2,129,861, issued'September 13,1938,for Lock-- forming of a bridge which may be cast outside of pin construction for fixed bridgework. 1 1 y the mouth and thereafter be permanently fixed In performing theinvention, the dental oper-- a in the mouth without employing the heretofore ator initially makes his preparations in'thep'a- =5:

used prongs or pins interengaging with teeth. 1 'tients mouthwherein' he grinds or cuts into' the .'An important advantage of the inventionlies enamel :of the anchor teeth at each side of the in the fact that following an initial preliminary spacingto be bridged.- Injthis preparation, the preparation *of the patients mouth, all of the operator cuts down the anchor teeth by an 0 work canbe done accurately on thebridge outamount which will allow for the thickness of the side of the patients mouth without the heretocast bridge to be thereafter fitted over those teeth, fore usual annoyance to the patient .and at the taking care to cut in cavity form with the necesv same time, by following the method ofthe insary retentive grooves and walls; When these vention, a perfect fit may be'made even in a large preparations have been completed, the bite is casting. I taken in the usualv and wellknown manner in A further primary object'o'f the invention is towax directly over the preparations and this war: provide a structure which may be permanently bite is then laid aside for future reference. fixed to teeth: within the patients mouth but at. The operator then makes a primary impresthe same time will provide relative movement si'on of the prepared teeth, using metal cups carbetween teeth as would ordinarily occur in masrying the impression material all in theusual and 'tication. A c well known' ma'nnerl The impressionmaterial 'By providing a structure and method of 'formwith its enclosing cup isleft over theprepared ing the structure wherebythe bridge is produced 'teeth and the operator proceeds with the second-f externally of the patients mouth, extreme accuary in'lpression which consists of taking a bridge racy as well as durability'is obtained together 'tray carryingplaster or some similar material as with the proper relation "in reference to the noris customarily employed and carrying thetray dimal bite.v rectly over the cups left on the preparation. These and many other objects and-advantages The plaster is allowed-to set about the primary of the invention will become apparent to those impression and then the entire combination, ina versed inthe art in the following description of cluding the primary and-"secondary impressions, 39

one particular method of performingthe'invenare removed. 'An impression is also taken of tion which is more or less diagrammatically illusthe opposing jaw to be employed later." All subtrated by the accompanying drawings, in which sequent construction ofthe bridge is then done Fig. 1 is a side elevation of-a crown bridge aroutside of the patients mouth. Usingv any suit-. ticulator carrying metal teeth; able. model alloy such as the usual amalgam, the .35

Fig' z tt plan e of t upperset frimary impressions are packed and built high teeth; enough from the tooth'impressions or molds 'to Fig, .3; a vertical longitudinal section through fo a a i end o each tooth which will the anchor teeth; hold theresultant tooth or preparation in a suitm Fig. 4, a like view in section following a rein- "able plaster or stone support' After the alloy 40 forcing operation; i i has set in thel'primary impression, the secondary Fig. 5, a like section illustrating a subsequent impression is coated" with any Suitable separating step of forming a casting pattern; i fiuid, poured as a stone modeL'and then-separat- Fig. 6,-avertical section through a mold coned. This results in giving a stone model with.

taining the pattern; metal teethas an exact duplicate in exact posi 4.5 Fig. 7, a bottom planview of the cast bridge tion of the prepared teeth in the'patients mouth. fitted in the articulator; ,The impression of the teeth in the-other jaw is Fig. 8, a side elevation of the'bridge fitted in likewise poured in a similar plaster-or model the articulator; v stone. These upper andlower models are then 9, a detail in vertical transverse section separated and are mounted on the'usual crown 50 of the dummy to the bridge attachment; and bridge articulator in the proper relationby em- F'ig. 10, a detail on a greatly enlarged scale of ploying. the wax bite which was originally taken the pivot connection embodied in the bridge. over the mouth bridge. This results in providing Like characters of reference indicate like parts the articulator with the opposing teeth as.indithroughout the several views in the drawin S-. 1 cated in Fig. 1., In the present description of s l2 of thezalzticulator enerally d si natedlby h numeral I3 is removed. The metal teeth H) and l I then have applied to them pure gold in sheet 4;

or plate form, such as 36 gauge. This gold It may be swaged but I prefer burnishing so as tocarry the thin soft gold Well over the ,meta1tteeth I and H to bring it into intimate contact with all of the varying angles and curvatures .ofwthe under cut and retentive grooves A. The gold l4 iscarried about the biting surfaces and the front, rear and-.sinside-esurfaces o'fa'the teeth to formemthin tissue 'zthick'nessi thereatomd. :The edges :of the :ness: .ofza casting :waxusuallyrne'terredrto rbycden- :tists,-..as pinkrcasting wax. eprefenably :ofztranslucentznature. 'Thezth-icknessxoftzthis waxildetermines :combination avith sthe thickness aof the matrix! and the;soldersthezresuitantz thickness \of :the-afinished 5 bridge. ".Referr-ingr toriiig. ;4, :this -wax .-'.coating is iindica-tedizby ctheztlfilms t5 sand t1 .onmtherrespective:teethiiflaand H.

Theaoperator =-.then wselects F from zzstoek ssuitable f-aciizigs:o'r:dumimrteeth, twozinithe:presentcexam pie, i which will the .-.c.arried :between the=..anchored teethtfl and l;l.".rheseqdummy teeth, ":t8 and --lt9,sFig- 5,:-may have: any zone vofvt-hewwell means "for: -.-anchoring :-;the dummy tooth :to .!;the bridgeattachment. .In'zthe :paitieularr form'therein shown :as one :possibility :only, I116 @dnmmy tooth, TvFig. :19, @is I of that --.type ihaving :a :slot' :20

I :thereiniof: circularncross section :fITOmaWhiCh? leads max 1 is applied "to these teeth *from their under sides i130 build 1 them up to the proper -:elevation and to give a contour l in the =wax corresponding to *the desiredsurfacepf the finished tooth. Re-

ferri-ng to -Figs. 5 and =10, the Wax 2-3, Fig. --5, is carried over {from the under sides of 'the teeth Wand t9 to join in and become an" integral part of the wax-coating l 6--on a-tooth- H1. The -wax '2'3, however, is kept separ-ate and-out of contact-with the wax-coating "l'l -on*the*to0th H. A-=pin-24 avax zcoatings. -a ;wax :1eadi'28 :runscfromthe ;;coating [6 ont-the havinga shank with any suitable retentive means herein shown as grooves 25, is mounted to have that shank extend into the wax which engages the tooth l9. i I

This pin 24is provided with a head 26 spherical in shape andv this head is embedded in the wax H which engages the tooth II. The translucent nature of the wax permits sufficient visibility of the embedded head as to permitthe desired 10- catingrthereofeand aftei tr im mi'ng of the wax.

. Rarticularsattention is directed to xtheliact that before the head 26 is embedded in the wax l0, its'is coated to give a film 21, Fig. 10, of a suitable anti-flux. This anti-flux is carried out sufficientlyfar on the neck or shank of the pin, ,..as .indicatedimFig. 10, as to coat that length of the shank which extends between the wax 23 and --tl1e wax t1 "This-aanti-fiux may be made out of anywsuitable material which'may be readily applied, preferably in a liquid form to give a uniformbcoating about ztherheadr 2.6 ':and' which :may be built-:rup:toardefinite zthickness. finenarticular-antieflux'rgiving:goodsatisfactionisxacomanon. brushingzorsprayin -clear;lacaueminrwhich carbon' or lampblack. has been; mixed. .The :anti-, flux-must spossess those -:-pr.operties of adhering 1 tightly to the metal 'withont'rubbing-voff readily,

and'alsoyof resisting-"heatupto around.:2',000rdei- 'grees :F. .101 at least up itovthe i zm'elting zpointsof the pin. This coatedxhead :26 is :then embedded in :thewa'x H i which:israboutithexmatrix ion'sthe tooth l l That mart i .of the. antiifiux :extendin? out ontozt-h'e shank ofithe:pinwisrpmferfibhtfoamed :ortscrapedcoff. v i

The next step is to attach sprue leads rtoathe .In :the :present .zcxample, yFfig- 5,

.tooth t0; arwax leadlfi:extends from the-max .223 mover 'tthe dummylteeth and a :third lead .430 extends fromthe :waxrcoating; 1-.orr'the toothi i I These three leads are brought togetherjntoira' common lead :3l whichiorthe pur ose :of: forming the :mold :may Joe a :metal about which thexwaxcmaygadhere. z'Rreferablyzwherc-zthe'rwax about-:the :teethi is removed-quite :-.a idistancerarid 11 0ut:.0f;.a directrline' with thei'resultant; lead .23 I, :an enlargement such as 32 is formed in theileadto provide :for expansion :of gases :in z-making :the :cast. ."After the; leads have been f formed a and. at- ,tachedrtherresultant;pattern of the bridge is-then carefully :i-withdrawn =.:fr 0m :the mteeth it!) -ami .l H the :matricesbeing Withdrawn the max, Fan-d then" the dummyxteeth i I18 ;;and l9 :arerpulledside Waysron *theattachmentsi :z2zrtoz remove them from the wax impressionsathereabout.

For convenience the-pattern is zthenisupported by a rubber stand 33 having a central bore there- ;through zwhichreceives tthe;.meta1'-.pin 3|. .This stand 33 is, of course, not essential butfisiused only as aJnatter 510i? xconvenience ato supporttthe 5 pattern and also to form a metalreeeivingscnp when'rthezpattern: is carried: inwtheimold 34 .as'indicated in Fig.1;6. i r

-:-Referring to :Fig; .6; the. pattern if ormedasabove indicated, is placed upside-down in -.=the:.m.oldi34 anda mixture of investment L-compound ori-any suitable medium is pourediinf1the-.mold 34 about the .--pattern; allowed to :set and dried out. 'Ihe,

mold is then heated to burn out'thewax'parts of the pattern. Thiswax lea ve's '--'little "or -no' i -esidue. passing "off largely in 1\ the form or gases. Therubber 33=is removed and thepatt-ern then takes the appearance as that indicated in'Fig. 6 wherein the-goldmatrix foreach tooth ill and- I l is carried 'by the wax, thedummy teeth' eonnecby any of the well known methods into'the 'cup 35 i'n'the mold, Fig. 6, and'casting is continued" tions 22 also'being' carried by the wax, as is also the pin 24. In reference to this pin, it is essential that the shank 24 which is embedded in that portion of the wax 23 be absolutely me of the anti-flux so that this shank may bond itself with the c'asted'metal." Furthermore, the investment compoundmusthe ofthat'n'ature'that the thin section which extends betweenthe. wax H and the wax 23 will rigidly support the exposed short length 01' the pin 24. This section or Wall is all that supports the pin" in casting.

The mold thus-prepared, as above indicated,-

is then ready for casting. 'Molten gold is cast until the gold has flowed "down into all parts of the moldand bonded withthematrices.- in re gard to thecasting, there must be a relative difference maintained between melting ranges of the various metalsemployed. For one example to hood of1750 degrees'F. The 18K. solder melts around 1360 degrees F5 Thecasting metal melts and flows at-around 1500degr'ees F. The pin 24 bridge is taken to the patients mouth to check has a melting point as high or higher than that of the pure gold. x

In casting the molten gold the gold will flow down and bond itself with the gold matrix in each case particularly through the solder about the matrix; the anti-flux about the head 26 will prevent bonding of the casting metal with the head; the casting metal will bond itself to the uncoatedpart of the shank of the pin;

and the gold will also bond itself to the ends of the dummy tooth attachments 22. Upon cooling,

the casting is removed from the mold and the sprue leads cut off andthe casting polished and finished up as the operator may see fit. The casting is carried back to the metal teeth l0 and I I in the stone M to check for fit and for finishing. Then the anti-flux 2'! which still re- 'mains about the head 26 within the metal36,

Fig. 10, is dissolved and washed out. Where the lacquer anti-flux isemployed, this operation may be performed by the use of any lacquer solvent, ether being suitable for the ordinary lacquer, as above indicated. The lacquer and carbon are entirely Washed out to leave a clearance between the is intended to support the end of the bridge at the tooth H to; prevent this action. Itis to be noted that the head 26 is cast .to be just within the finished metal 36, and that by reason of the removal of the anti-flux on that part of the head and shank of the pin originally covered, the pin may rock relative to the tooth II. This motion I is, of course, limited butis, absolutely essential that it be provided for inv order to prevent breaking of the bridge or cement retaining it under stress and strain set up when the bridge is in use. The dummyyteethldandlfl are re-engaged with the attachments 22 and then the entire for final fit. If the fit is correct, the inside surfaces of the matrices are coated with a suitable cement as are also the sockets and head of the into the mold I chor teeth are driedand'the bridge is then placed .inl the patients mouth and seatedon theanchor teeth and excess cement expelled to allow bridge to settle: for normalocclusion. The cement is allowed to set whereby the bridge is then permanently anchored to the anchor teeth lfl and II. The operation is completed by burnishing down the exposed edges of the original gold matrix 'on each'tooth so as to provide a durable and complete seal between the bridge andthe anchor teeth with a minimum exposed cement line.

T The fitted bridge casting after beingfinished preparatory to being placed in the patients mouth willhave an appearance in side elevation when attached to the teeth somewhat as indicated in attaching parts of the dummy teeth. Thean- Fig. 8'. It'is obvious that', while' I have herein shown the bridge as replacing or carrying'two teeth between the anchor teeth, the same construction may be employed entirely around the mouth between spaced anchor teeth without hav ing to employ a plate or the like as has been the usual practice heretofore. The dummy teeth 18 and l9will fit'down-a'ga'lnst the tissue in the patients mouth with just that degree of contact as would ordinarily prevent foreign matter from entering thereunder, but at the same time the bridge will so support these teeth as to permit the entrance of dental floss thereunder'for cleans- In other words, I can use much less and better 1 metal than in the soldered types for the same strength and secure greatercomfort for the patient. 1 Z It is thus to be'seen that I have provided a which are distinctly advantageous over the practices heretofore employed, and While I have herei structure and method of forming that structure in shown and described the one particular struci ture and method, it isobvious that variations may be employed, such as having the cast metal teeth I0 and II in the articulator stone to be provided with removable shanks in relation to the stone, and in varying the sequence of the steps, all without departing from the spirit of the invention, and I, therefore, do not desire to be'limited to that precise form beyond the limitations as may be imposed by the following claims.

Iclaim: I

1. In a method'of forming a cast metal bridge to have an articulatedsupport employing a pre-- formed metal pin having a ball on one end, those steps of working a thin. soft gold sheet into intimate contact over a tooth preparation, building upwax over that sheet to. the desired configura tion and elevation, applying one. or more coats of a lacquer-type anti-flux to a given predetermined thickness .over, said ball, embedding that ball in said wax to have the pin project laterally therefrom and. to have the wax surround the outer side of the ball adjacent said pin,embedding the shank of said pin in wax of another bridge part to leave a clearance between the first and second wax, placing an investment mixture around both of said-waxed parts carrying said mixture into said clearance to completely surround and contact said shank appearing thereacross, heating. the, invested parts to remove all 01 the wax,casting with gold to fill the wax shaped. investment. cavities. to have. said; casting gold: flow' aroundithe shank: of; the pinomtheone side of the pin supporting investment and around the coated head. on the other side, removing the investment, and washing out. the-anti-fiux from the ball in the. socket formed by the metal cast thereover.

2. For definitely locating and fixing a pin for an articulated joint in a dental bridge, those stepswhich consist of building up. wax crowns, spacing one wax crown from another by embedding the rounded anti-flux coated head of. a pin in the wax of one crown and embedding theshank of the pin inan adjacent wax crown toleave a. short length ofthe-shank exposed. be tween those two crowns whereb-y the pin carries and spaces apart those crowns the desired clear.- ancedistance, investing the wax crown: thus tied together tohave investment compound flow by a narrow section betweenqthose' wax crowns to surround and'support:said-exposed shank; length, and removing the wax from the investment to leave said pin to be located. and rigidly supported entirely by said investment section, whereby the pin will be located in the casting: subsequently poured to be in the exact relationship to the finished. crownsas originally determined in the wax. crowns.

3-. For definitely locating and fixing'a-pin for an. articulated'jointin a dental bridge; those. steps which consist of building up wax. crowns, spacing.

one wax crown from another byembedding the rounded, anti-flux coated head of a pin in the wax of. one crown and embedding; the shank of the pin in anadjacent wax crown to leave a short length of the shank exposed betweenthose; two crowns whereby the pin carries and spacesapart those crowns the desired clearance distance-investing the wax crown thustied together to have investment compound flow bya narrow section between those wax crowns to surround and support said exposed shank length,andrremoving: the wax from. theinvestment to leavesaid pin to be located and rigidly supported entirely by said investment section, whereby the=pin will be located in the casting subsequently poured. to be in the exact relationship to thefinished crowns as originally determined in the wax crowns, said shank being coated with said anti-flux. overasaid exposedv length: to have said section engage the shank about said anti-flux.

CHARLES DALE MORTON. 

